The present invention teaches a supplemental or optional improvement to the ultrasonic streaming current detector apparatus of co-pending application, Ser. No. 375,577. Particularly, the present invention features a passageway means for inducing intermittently a suitable cleaning fluid, such as deionized or distilled water, or sodium hypochlorite, through a cleaning fluid inlet provided in serial combination with an adjustable valve provided in fluid communication with the bottom of a connector receptacle, which is in turn connected in fluid communication with the longitudinal element 4 of cross-shaped member 2, reference being had to said co-pending application, said passageway means ultimately fluidly communicating with a bore provided in the bottom surface of dielectric cap 20 for thereby facilitating the injection of said cleaning fluid forcibly against piston 42 and lands 43 thereof, and dielectric sleeve 19, inter alia. The setting of said adjustable valve connected in series to said cleaning fluid inlet will determine the force with which said cleaning fluid will be injected against piston 42 and lands 43 thereof, and dielectric sleeve 19, inter alia. The setting selected should allow said cleaning fluid to be injected with a force sufficient enough to cause any material, especially material containing charge-influencing species, that may have accumulated on lands 43 of piston 42 and/or in the cavity formed by piston 42, the bottom of sleeve 19 and dielectric cap 20 to be forced out between piston 42 and sleeve 19 and expelled through apertures 22, 23 into reservoir 12 and thence through egress means 13. It is important to understand that the jet wash apparatus of the present invention may be employed in addition to or in lieu of the ultrasonic cleaning device 45 of the ultrasonic streaming current detector of said co-pending application, for preventing the accumulation of any material, especially material containing charge-influencing species on or around piston 42 or dielectric cap 20. It has been discovered through experience that the readings generated by the ultrasonic streaming current detector have been inaccurate when the test fluid accumulated impurities and its concentration and make-up drastically changed. This situation has only been found to occur in extremely harsh applications of the present invention. The only applications in which the ultrasonic streaming current detector failed were when the test fluid was simulated white water and tray water as found in a paper making machine, or river water. In these situations, depending on the nature of the liquid being sampled, the jet wash apparatus of the present invention has been utilized with success, either independently, or in conjunction with the ultrasonic cleaning device 45 of the ultrasonic streaming current detector of said co-pending application.
The jet wash can be intermittently controlled manually or automatically to induce the cleaning action as indicated, particularly when the instrument can not be set to zero as a result of impurities in the chamber.